Multi-speed dual-clutch planetary transmission mechanisms having a stationary gear member and one brake

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least six forward speed ratios and one reverse speed ratio. The transmission family members include four planetary gear sets, two input clutches, eight or nine torque transmitting mechanisms, two fixed interconnections, and one grounded planetary gear member. The invention provides a low content multi-speed dual clutch transmission mechanism wherein the two input clutches alternately connect the engine to realize odd and even number speed ratio ranges. The torque transmitting mechanisms provide connections between various gear members, the fixed interconnections, the first input clutch, the output shaft, and the transmission housing, and are operated in combinations of three to establish at least six forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

[0001] The present invention relates to a family of power transmissionshaving two input clutches which selectively connect an input shaft tofirst and second pairs of planetary gear sets to provide at least sixforward speed ratios and one reverse speed ratio.

BACKGROUND OF THE INVENTION

[0002] Passenger vehicles include a powertrain that is comprised of anengine, multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times.

[0003] A primary focus of transmission and engine design work is in thearea of increasing vehicle fuel efficiency. Manual transmissionstypically provide improved vehicle fuel economy over automatictransmissions because automatic transmissions use a torque converter forvehicle launch and multiple plate hydraulically-applied clutches forgear engagement. Clutches of this type, left unengaged or idling, imposea parasitic drag torque on a drive line due to the viscous shearingaction which exists between the plates and discs rotating at differentspeeds relative to one another. This drag torque adversely affectsvehicle fuel economy for automatic transmissions. Also, the hydraulicpump that generates the pressure needed for operating theabove-described clutches further reduces fuel efficiency associated withautomatic transmissions. Manual transmissions eliminate these problems.

[0004] While manual transmissions are not subject to the above describedfuel efficiency related problems, manual transmissions typically providepoor shift quality because a significant torque interruption is requiredduring each gear shift as the engine is disengaged from the transmissionby the clutch to allow shafts rotating at different speeds to besynchronized.

[0005] So called “automated manual” transmissions provide electronicshifting in a manual transmission configuration which, in certaincircumstances, improves fuel efficiency by eliminating the parasiticlosses associated with the torque converter and hydraulic pump neededfor clutching. Like manual transmissions, a drawback of automated manualtransmissions is that the shift quality is not as high as an automatictransmission because of the torque interruption during shifting.

[0006] So called “dual-clutch automatic” transmissions also eliminatethe torque converter and replace hydraulic clutches with synchronizersbut they go further to provide gear shift quality which is superior tothe automated manual transmission and similar to the conventionalautomatic transmission, which makes them quite attractive. However, mostknown dual-clutch automatic transmissions include a lay shaft orcountershaft gear arrangement, and have not been widely applied invehicles because of their complexity, size and cost. For example, a dualclutch lay shaft transmission could require eight sets of gears, twoinput/shift clutches and seven synchronizers/dog clutches to provide sixforward speed ratios and a reverse speed ratio. An example of adual-clutch automatic transmission is described in U.S. Pat. No.5,385,064, which is hereby incorporated by reference.

SUMMARY OF THE INVENTION

[0007] The invention provides a low content multi-speed dual-clutchtransmission family utilizing planetary gear sets rather than lay shaftgear arrangements. In particular, the invention includes four planetarygear sets, two input/shift clutches, and nine selectable torquetransmitting mechanisms to provide at least six forward speed ratios anda reverse speed ratio.

[0008] According to one aspect of the invention, the family oftransmissions has four planetary gear sets, each of which includes afirst, second and third member, which members may comprise a sun gear,ring gear, or a planet carrier assembly member.

[0009] In referring to the first, second, third and fourth gear sets inthis description and in the claims, these sets may be counted “first” to“fourth” in any order in the drawings (i.e. left-to-right,right-to-left, etc.).

[0010] In another aspect of the present invention, each of the planetarygear sets may be of the single pinion type or of the double pinion type.

[0011] In yet another aspect of the present invention, the first memberof the first planetary gear set is continuously connected with the firstmember of the second planetary gear set through a first interconnectingmember.

[0012] In yet another aspect of the present invention, a member of thefirst or second planetary gear set is continuously connected with thefirst member of the third planetary gear set and the output shaftthrough a second interconnecting member.

[0013] In yet another aspect of the present invention, the first memberof the fourth planetary gear set is continuously connected with astationary member (transmission housing).

[0014] In accordance with a further aspect of the invention, a firstinput clutch selectively connects the input shaft with members of thefirst and second planetary gear set through other torque-transmittingmechanisms, such as synchronizers.

[0015] In accordance with another aspect of the present invention, asecond input clutch selectively connects the input shaft with the secondmember of the third planetary gear set.

[0016] In another aspect of the invention, first and second torquetransmitting mechanisms, such as synchronizers, selectively connectmembers of the first and second planetary gear sets with the first inputclutch.

[0017] In another aspect of the invention, third and fourth torquetransmitting mechanisms, such as synchronizers, selectively connectmembers of the first or second planetary gear set with other members ofthe first or second planetary gear set, or with the first input clutch.

[0018] In still a further aspect of the invention, fifth, sixth, seventhand eighth torque transmitting mechanisms, such as synchronizers,selectively connect members of the third planetary gear set with secondand third members of the fourth planetary gear set.

[0019] In still another aspect of the invention, a ninth torquetransmitting mechanism, such as braking synchronizer, selectivelyconnects a member of the first or second planetary gear set with thestationary member.

[0020] In accordance with a further aspect of the invention, the inputclutches and torque transmitting mechanisms are selectively engaged incombinations of at least three to provide at least six forward speedratios and a reverse speed ratio.

[0021] In accordance with a further aspect of the invention, the ninetorque transmitting mechanisms may comprise synchronizers.

[0022] In accordance with a further aspect of the invention, the firstinput clutch is applied for odd number speed ranges, and the secondinput clutch is applied for even number speed ranges, or vice versa.

[0023] In another aspect of the invention, the first input clutch andthe second input clutch are interchanged (i.e. alternately engaged) toshift from odd number speed range to even number speed range, or viceversa.

[0024] In accordance with a further aspect of the invention, eachselected torque transmitting mechanism for a new speed ratio is engagedprior to shifting of the input clutches to achieve shifts without torqueinterruptions.

[0025] In accordance with a further aspect of the invention, at leastone pair of synchronizers is executed as a double synchronizer to reducecost and package size.

[0026] In accordance with a further aspect of the invention, the firstinput clutch can be eliminated and the first and second torquetransmitting mechanisms can be used as input clutches to further reducecontent.

[0027] In accordance with a further aspect of the invention, at leastone of the torque transmitting mechanisms can be eliminated to realizefive forward speed ratios and a reverse speed ratio.

[0028] The above objects, features, advantages, and other objects,features, and advantages of the present invention are readily apparentfrom the following detailed description of the best modes for carryingout the invention when taken in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

[0030]FIG. 1b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1a;

[0031]FIG. 2a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0032]FIG. 2b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2a;

[0033]FIG. 3a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0034]FIG. 3b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3a;

[0035]FIG. 4a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0036]FIG. 4b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4a;

[0037]FIG. 5a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0038]FIG. 5b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5a;

[0039]FIG. 6a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0040]FIG. 6b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6a;

[0041]FIG. 7a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0042]FIG. 7b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7a;

[0043]FIG. 8a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0044]FIG. 8b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8a;

[0045]FIG. 9a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

[0046]FIG. 9b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Referring to the drawings, wherein like characters represent thesame or corresponding parts throughout the several views, there is shownin FIG. 1a a powertrain 10 having a conventional engine 12, a planetarytransmission 14, and a conventional final drive mechanism 16.

[0048] The planetary transmission 14 includes an input shaft 17continuously connected with the engine 12, a planetary gear arrangement18, and an output shaft 19 continuously connected with the final drivemechanism 16. The planetary gear arrangement 18 includes four planetarygear sets 20, 30, 40 and 50.

[0049] The planetary gear set 20 includes a sun gear member 22, a ringgear member 24, and a planet carrier assembly member 26. The planetcarrier assembly member 26 includes a plurality of pinion gears 27rotatably mounted on a carrier member 29 and disposed in meshingrelationship with both the sun gear member 22 and the ring gear member24.

[0050] The planetary gear set 30 includes a sun gear member 32, a ringgear member 34, and a planet carrier assembly member 36. The planetcarrier assembly member 36 includes a plurality of pinion gears 37rotatably mounted on a carrier member 39 and disposed in meshingrelationship with both the sun gear member 32 and the ring gear member34.

[0051] The planetary gear set 40 includes a sun gear member 42, a ringgear member 44, and a planet carrier assembly member 46. The planetcarrier assembly member 46 includes a plurality of intermeshing piniongears 47, 48 rotatably mounted on a carrier member 49 and disposed inmeshing relationship with the ring gear member 44 and the sun gearmember 42, respectively.

[0052] The planetary gear set 50 includes a sun gear member 52, a ringgear member 54, and a planet carrier assembly member 56. The planetcarrier assembly member 56 includes a plurality of pinion gears 57rotatably mounted on a carrier member 59 and disposed in meshingrelationship with both the sun gear member 52 and the ring gear member54.

[0053] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 20, 30, 40 and 50 are divided into first andsecond transmission subsets 60, 61 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 60 includes planetary gear sets 20 and 30, andtransmission subset 61 includes planetary gear sets 40 and 50. Theoutput shaft 19 is continuously connected with members of both subsets60 and 61.

[0054] As mentioned above, the first and second input clutches 62, 63are alternatively engaged for transmitting power from the input shaft 17to transmission subset 60 or transmission subset 61. The first andsecond input clutches 62, 63 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 60, 61 prior to engaging therespective input clutches 62, 63. The preselection is achieved by meansof electronically controlled synchronizers. As shown, the planetary geararrangement includes nine torque transmitting mechanisms 64, 65, 66, 67,68, 69, 70, 71 and 72. The torque transmitting mechanism 64 comprises abraking synchronizer, and the torque transmitting mechanisms 65, 66, 67,68, 69, 70, 71 and 72 comprise rotating synchronizers.

[0055] By way of example, synchronizers which may be implemented as therotating and/or braking synchronizers referenced herein are shown in thefollowing patents, each of which are incorporated by reference in theirentirety: U.S. Pat. Nos. 5,651,435; 5,975,263; 5,560,461; 5,641,045;5,497,867; 6,354,416.

[0056] The braking synchronizers and rotating synchronizers arereferenced in the claims as follows: first and second torquetransmitting mechanisms 65, 66; third and fourth torque transmittingmechanisms 67, 68; fifth, sixth, seventh and eighth torque transmittingmechanisms 69, 70, 71, 72; and ninth torque transmitting mechanism 64.Other family members are similarly referenced in the claims (i.e. firstand second torque transmitting mechanisms connected between input shaftand first and second planetary gear sets; third and fourth torquetransmitting mechanisms of left transmission subset in Figures; fifth,sixth, seventh and eighth torque transmitting mechanisms of righttransmission subset; and braking synchronizer).

[0057] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 60, 61 (i.e. through the clutch 62to synchronizers 65, 66, 67, and through clutch 63 to ring gear member44). The ring gear member 24 is continuously connected with the sun gearmember 32 through the interconnecting member 74. The planet carrierassembly member 46 is continuously connected with the ring gear member34 and the output shaft 19 through the interconnecting member 76. Thering gear member 54 is continuously connected with the transmissionhousing 80.

[0058] The planet carrier assembly member 26 is selectively connectablewith the transmission housing 80 through the braking synchronizer 64.The sun gear member 32 is selectively connectable with the input shaft17 through the input clutch 62 and the rotating synchronizer 65. The sungear member 22 is selectively connectable with the input shaft 17through the input clutch 62 and the rotating synchronizer 66. The planetcarrier assembly member 36 is selectively connectable with the inputshaft 17 through the input clutch 62 and the rotating synchronizer 67.The planet carrier assembly member 26 is selectively connectable withthe planet carrier assembly member 36 through the rotating synchronizer68. The planet carrier assembly member 46 is selectively connectablewith the planet carrier assembly member 56 through the rotatingsynchronizer 69. The planet carrier assembly member 46 is selectivelyconnectable with the sun gear member 52 through the rotatingsynchronizer 70. The sun gear member 42 is selectively connectable withthe planet carrier assembly member 56 through the rotating synchronizer71. The sun gear member 42 is selectively connectable with the sun gearmember 52 through the rotating synchronizer 72.

[0059] As shown in FIG. 1b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio.

[0060] The reverse speed ratio is established with the engagement of theinput clutch 62, the braking synchronizer 64 and the rotatingsynchronizers 65, 68. The input clutch 62 and the rotating synchronizer65 connect the sun gear member 32 to the input shaft 17. The brakingsynchronizer 64 connects the planet carrier assembly member 26 to thetransmission housing 80. The rotating synchronizer 68 connects theplanet carrier assembly member 26 to the planet carrier assembly member36. The ring gear member 24 and the sun gear member 32 rotate at thesame speed as the input shaft 17. The planet carrier assembly members26, 36 do not rotate. The ring gear member 34 and the planet carrierassembly member 46 rotate at the same speed as the output shaft 19. Thering gear member 34, and therefore the output shaft 19, rotates at aspeed determined from the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The numericalvalue of the reverse speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 30.

[0061] The first forward speed ratio is established with the engagementof the input clutch 62, the braking synchronizer 64 and the rotatingsynchronizers 66, 68. The input clutch 62 and the rotating synchronizer66 connect the sun gear member 22 to the input shaft 17. The brakingsynchronizer 64 connects the planet carrier assembly member 26 to thetransmission housing 80. The rotating synchronizer 68 connects theplanet carrier assembly member 26 to the planet carrier assembly member36. The sun gear member 22 rotates at the same speed as the input shaft17. The planet carrier assembly members 26, 36 do not rotate. The ringgear member 24 rotates at the same speed as the sun gear member 32. Thering gear member 24 rotates at a speed determined from the speed of thesun gear member 22 and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The ring gear member 34 and the planet carrierassembly member 46 rotate at the same speed as the output shaft 19. Thering gear member 34, and therefore the output shaft 19, rotates at aspeed determined from the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The numericalvalue of the first forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 20, 30.

[0062] The second forward speed ratio is established with the engagementof the input clutch 63 and the rotating synchronizers 69, 72. The inputclutch 63 connects the ring gear member 44 to the input shaft 17. Therotating synchronizer 69 connects the planet carrier assembly member 46to the planet carrier assembly member 56. The rotating synchronizer 72connects the sun gear member 42 to the sun gear member 52. The sun gearmember 42 rotates at the same speed as the sun gear member 52. Theplanet carrier assembly members 46, 56 rotate at the same speed as theoutput shaft 19. The ring gear member 44 rotates at the same speed asthe input shaft 17. The planet carrier assembly member 46, and thereforethe output shaft 19, rotates at a speed determined from the speed of thering gear member 44, the speed of the sun gear member 42 and the ringgear/sun gear tooth ratio of the planetary gear set 40. The ring gearmember 54 does not rotate. The planet carrier assembly member 56 rotatesat a speed determined from the speed of the sun gear member 52 and thering gear/sun gear tooth ratio of the planetary gear set 50. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets40, 50.

[0063] The third forward speed ratio is established with the engagementof the input clutch 62 and the rotating synchronizer 65, 67 and 68. Inthis configuration, the input shaft 17 is directly connected to theoutput shaft 19. The numerical value of the third forward speed ratio is1.

[0064] The fourth forward speed ratio is established with the engagementof the input clutch 63 and the rotating synchronizers 70, 71. The inputclutch 63 connects the ring gear member 44 to the input shaft 17. Therotating synchronizer 70 connects the planet carrier assembly member 46to the sun gear member 52. The rotating synchronizer 71 connects the sungear member 42 to the planet carrier assembly member 56. The sun gearmember 42 rotates at the same speed as the planet carrier assemblymember 56. The planet carrier assembly member 46 and the sun gear member52 rotate at the same speed as the output shaft 19. The ring gear member44 rotates at the same speed as the input shaft 17. The planet carrierassembly member 46, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 44, the speed ofthe sun gear member 42 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The ring gear member 54 does not rotate. Theplanet carrier assembly member 56 rotates at a speed determined from thespeed of the sun gear member 52 and the ring gear/sun gear tooth ratioof the planetary gear set 50. The numerical value of the fourth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 40, 50.

[0065] The fifth forward speed ratio is established with the engagementof the input clutch 62, the braking synchronizer 64 and the rotatingsynchronizers 66, 67. The input clutch 62 and the rotating synchronizers66, 67 connect the sun gear member 22 and the planet carrier assemblymember 36 to the input shaft 17. The braking synchronizer 64 connectsthe planet carrier assembly member 26 to the transmission housing 80.The sun gear member 22 and the planet carrier assembly member 36 rotateat the same speed as the input shaft 17. The planet carrier assemblymember 26 does not rotate. The ring gear member 24 rotates at the samespeed as the sun gear member 32. The ring gear member 24 rotates at aspeed determined from the speed of the sun gear member 22 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The ring gearmember 34 and the planet carrier assembly member 46 rotate at the samespeed as the output shaft 19. The ring gear member 34, and therefore theoutput shaft 19, rotates at a speed determined from the speed of theplanet carrier assembly member 36, the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thenumerical value of the fifth forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 20, 30.

[0066] The sixth forward speed ratio is established with the engagementof the input clutch 63 and the rotating synchronizers 71, 72. The inputclutch 63 connects the ring gear member 44 to the input shaft 17. Therotating synchronizer 71 connects the sun gear member 42 to the planetcarrier assembly member 56. The rotating synchronizer 72 connects thesun gear member 42 to the sun gear member 52. The sun gear member 42 andthe planetary gear set 50 do not rotate. The planet carrier assemblymember 46 rotates at the same speed as the output shaft 19. The ringgear member 44 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 46, and therefore the output shaft 19,rotates at a speed determined from the speed of the ring gear member 44and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the sixth forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratio of the planetary gear set 40.

[0067] As set forth above, the engagement schedule for the torquetransmitting mechanisms is shown in the truth table of FIG. 1b. Thistruth table also provides an example of speed ratios that are availableutilizing the ring gear/sun gear tooth ratios given by way of example inFIG. 1b. The R1/S1 value is the tooth ratio of the planetary gear set20; the R2/S2 value is the tooth ratio of the planetary gear set 30; theR3/S3 value is the tooth ratio of the planetary gear set 40; and theR4/S4 value is the tooth ratio of the planetary gear set 50. Also, thechart of FIG. 1b describes the ratio steps that are attained utilizingthe sample of tooth ratios given. For example, the step ratio betweenfirst and second forward speed ratios is 1.95, while the step ratiobetween the reverse and first forward ratio is −0.50. Those skilled inthe art will recognize that since torque transmitting mechanisms 65 and66 are connected to a common member, input clutch 62, and they are notengaged at the same time for any of the speed ratios, the pair can beexecuted as a double synchronizer to reduce content and cost. Similarly,torque transmitting mechanisms pair 70 and 72 can be implemented as adouble synchronizer.

[0068]FIG. 2a shows a powertrain 110 having a conventional engine 12, aplanetary transmission 114, and a conventional final drive mechanism 16.The planetary transmission 114 includes an input shaft 17 connected withthe engine 12, a planetary gear arrangement 118, and an output shaft 19connected with the final drive mechanism 16. The planetary geararrangement 118 includes four planetary gear sets 120, 130, 140 and 150.

[0069] The planetary gear set 120 includes a sun gear member 122, a ringgear member 124, and a planet carrier assembly member 126. The planetcarrier assembly member 126 includes a plurality of pinion gears 127rotatably mounted on a carrier member 129 and disposed in meshingrelationship with both the sun gear member 122 and the ring gear member124.

[0070] The planetary gear set 130 includes a sun gear member 132, a ringgear member 134, and a planet carrier assembly member 136. The planetcarrier assembly member 136 includes a plurality of pinion gears 137rotatably mounted on a carrier member 139 and disposed in meshingrelationship with both the sun gear member 132 and the ring gear member134.

[0071] The planetary gear set 140 includes a sun gear member 142, a ringgear member 144, and a planet carrier assembly member 146. The planetcarrier assembly member 146 includes a plurality of intermeshing piniongears 147, 148 rotatably mounted on a carrier member 149 and disposed inmeshing relationship with the ring gear member 144 and the sun gearmember 142, respectively.

[0072] The planetary gear set 150 includes a sun gear member 152, a ringgear member 154, and a planet carrier assembly member 156. The planetcarrier assembly member 156 includes a plurality of intermeshing piniongears 157, 158 rotatably mounted on a carrier member 159 and disposed inmeshing relationship with the ring gear member 154 and the sun gearmember 152, respectively.

[0073] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 120, 130, 140 and 150 are divided into firstand second transmission subsets 160, 161 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 160 includes planetary gear sets 120 and 130, andtransmission subset 161 includes planetary gear sets 140 and 150. Theoutput shaft 19 is continuously connected with members of both subsets160 and 161.

[0074] As mentioned above, the first and second input clutches 162, 163are alternatively engaged for transmitting power from the input shaft 17to transmission subset 160 or transmission subset 161. The first andsecond input clutches 162, 163 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 160, 161 prior to engagingthe respective input clutches 162, 163. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms164, 165, 166, 167, 168, 169, 170, 171 and 172. The torque transmittingmechanism 164 comprises a braking synchronizer, and the torquetransmitting mechanisms 165, 166, 167, 168, 169, 170, 171 and 172comprise rotating synchronizers.

[0075] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 160, 161 (i.e. through the clutch162 to synchronizers 165, 166, 167 and through clutch 163 to ring gearmember 144). The ring gear member 124 is continuously connected with thesun gear member 132 through the interconnecting member 174. The planetcarrier assembly member 146 is continuously connected with the ring gearmember 134 and the output shaft 19 through the interconnecting member176. The planet carrier assembly member 156 is continuously connectedwith the transmission housing 180.

[0076] The planet carrier assembly member 126 is selectively connectablewith the transmission housing 180 through the braking synchronizer 164.The sun gear member 132 is selectively connectable with the input shaft17 through the input clutch 162 and the rotating synchronizer 165. Thesun gear member 122 is selectively connectable with the input shaft 17through the input clutch 162 and the rotating synchronizer 166. Theplanet carrier assembly member 136 is selectively connectable with theinput shaft 17 through the input clutch 162 and the rotatingsynchronizer 167. The planet carrier assembly member 126 is selectivelyconnectable with the planet carrier assembly member 136 through therotating synchronizer 168. The planet carrier assembly member 146 isselectively connectable with the ring gear member 154 through therotating synchronizer 169. The planet carrier assembly member 146 isselectively connectable with the sun gear member 152 through therotating synchronizer 170. The sun gear member 142 is selectivelyconnectable with the ring gear member 154 through the rotatingsynchronizer 171. The sun gear member 142 is selectively connectablewith the sun gear member 152 through the rotating synchronizer 172.

[0077] As shown in FIG. 2b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio.

[0078] The reverse speed ratio is established with the engagement of theinput clutch 162, the braking synchronizer 164 and the rotatingsynchronizers 165, 168. The input clutch 162 and the rotatingsynchronizer 165 connect the sun gear member 132 to the input shaft 17.The braking synchronizer 164 connects the planet carrier assembly member126 to the transmission housing 180. The rotating synchronizer 168connects the planet carrier assembly member 126 to the planet carrierassembly member 136. The sun gear member 132 rotates at the same speedas the input shaft 17. The planet carrier assembly members 126, 136 donot rotate. The ring gear member 134 and the planet carrier assemblymember 146 rotate at the same speed as the output shaft 19. The ringgear member 134, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the sun gear member 132 and the ringgear/sun gear tooth ratio of the planetary gear set 130.

[0079] The first forward speed ratio is established with the engagementof the input clutch 162, the braking synchronizer 164 and the rotatingsynchronizers 166, 168. The input clutch 162 and the rotatingsynchronizer 166 connect the sun gear member 122 to the input shaft 17.The braking synchronizer 164 connects the planet carrier assembly member126 to the transmission housing 180. The rotating synchronizer 168connects the planet carrier assembly member 126 to the planet carrierassembly member 136. The sun gear member 122 rotates at the same speedas the input shaft 17. The planet carrier assembly members 126, 136 donot rotate. The ring gear member 124 rotates at the same speed as thesun gear member 132. The ring gear member 124 rotates at a speeddetermined from the speed of the sun gear member 122 and the ringgear/sun gear tooth ratio of the planetary gear set 120. The ring gearmember 134 and the planet carrier assembly member 146 rotate at the samespeed as the output shaft 19. The ring gear member 134, and thereforethe output shaft 19, rotates at a speed determined from the speed of thesun gear member 132 and the ring gear/sun gear tooth ratio of theplanetary gear set 130. The numerical value of the first forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 120, 130.

[0080] The second forward speed ratio is established with the engagementof the input clutch 163 and the rotating synchronizer 169, 172. Theinput clutch 163 connects the ring gear member 144 to the input shaft17. The rotating synchronizer 169 connects the planet carrier assemblymember 146 to the ring gear member 154. The rotating synchronizer 172connects the sun gear member 142 to the sun gear member 152. The sungear member 142 rotates at the same speed as the sun gear member 152.The planet carrier assembly member 146 and the ring gear member 154rotate at the same speed as the output shaft 19. The ring gear member144 rotates at the same speed as the input shaft 17. The planet carrierassembly member 146, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 144, the speedof the sun gear member 142 and the ring gear/sun gear tooth ratio of theplanetary gear set 140. The planet carrier assembly member 156 does notrotate. The ring gear member 154 rotates at a speed determined from thespeed of the sun gear member 152 and the ring gear/sun gear tooth ratioof the planetary gear set 150. The numerical value of the second forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 140, 150.

[0081] The third forward speed ratio is established with the engagementof the input clutch 162 and the rotating synchronizers 165, 167 and 168.In this configuration, the input shaft 17 is directly connected to theoutput shaft 19. The numerical value of the third forward speed ratio is1.

[0082] The fourth forward speed ratio is established with the engagementof the input clutch 163 and the rotating synchronizers 170, 171. Theinput clutch 163 connects the ring gear member 144 to the input shaft17. The rotating synchronizer 170 connects the planet carrier assemblymember 146 to the sun gear member 152. The rotating synchronizer 171connects the sun gear member 142 to the ring gear member 154. The sungear member 142 rotates at the same speed as the ring gear member 154.The planet carrier assembly member 146 and the sun gear member 152rotate at the same speed as the output shaft 19. The ring gear member144 rotates at the same speed as the input shaft 17. The planet carrierassembly member 146, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 144, the speedof the sun gear member 142 and the ring gear/sun gear tooth ratio of theplanetary gear set 140. The planet carrier assembly member 156 does notrotate. The ring gear member 154 rotates at a speed determined from thespeed of the sun gear member 152 and the ring gear/sun gear tooth ratioof the planetary gear set 150. The numerical value of the fourth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 140, 150.

[0083] The fifth forward speed ratio is established with the engagementof the input clutch 162, the braking synchronizer 164 and the rotatingsynchronizers 166, 167. The input clutch 162 and the rotatingsynchronizers 166, 167 connect the sun gear member 122 and the planetcarrier assembly member 136 to the input shaft 17. The brakingsynchronizer 164 connects the planet carrier assembly member 126 to thetransmission housing 180. The sun gear member 122 and the planet carrierassembly member 136 rotate at the same speed as the input shaft 17. Theplanet carrier assembly member 126 does not rotate. The ring gear member124 rotates at the same speed as the sun gear member 132. The ring gearmember 124 rotates at a speed determined from the speed of the sun gearmember 122 and the ring gear/sun gear tooth ratio of the planetary gearset 120. The ring gear member 134 and the planet carrier assembly member146 rotate at the same speed as the output shaft 19. The ring gearmember 134, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 136, thespeed of the sun gear member 132 and the ring gear/sun gear tooth ratioof the planetary gear set 130. The numerical value of the fifth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 120, 130.

[0084] The sixth forward speed ratio is established with the engagementof the input clutch 163 and the rotating synchronizer 171, 172. Theinput clutch 163 connects the ring gear member 144 to the input shaft17. The rotating synchronizer 171 connects the sun gear member 142 tothe ring gear member 154. The rotating synchronizer 172 connects the sungear member 142 to the sun gear member 152. The sun gear member 142 andthe planetary gear set 150 do not rotate. The planet carrier assemblymember 146 rotates at the same speed as the output shaft 19. The ringgear member 144 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 146, and therefore the output shaft 19,rotates at a speed determined from the speed of the ring gear member 144and the ring gear/sun gear tooth ratio of the planetary gear set 140.The numerical value of the sixth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set140.

[0085] As set forth above, the truth table of FIG. 2b describes theengagement sequence of the torque transmitting mechanisms utilized toprovide a reverse drive ratio and six forward speed ratios. The truthtable also provides an example of the ratios that can be attained withthe family members shown in FIG. 2a utilizing the sample tooth ratiosgiven in FIG. 2b. The R1/S1 value is the tooth ratio of the planetarygear set 120; the R2/S2 value is the tooth ratio of the planetary gearset 130; the R3/S3 value is the tooth ratio of the planetary gear set140; and the R4/S4 value is the tooth ratio of the planetary gear set150. Also shown in FIG. 2b are the ratio steps between single stepratios in the forward direction as well as the reverse to first ratiostep. For example, the first to second step ratio is 1.66. Those skilledin the art will recognize that since torque transmitting mechanisms 165and 166 are connected to a common member, input clutch 162, and they arenot engaged at the same time for any of the speed ratios, the pair canbe executed as a double synchronizer to reduce content and cost.Similarly, torque transmitting mechanisms pair 170 and 172 can beimplemented as a double synchronizer.

[0086] Turning the FIG. 3a, a powertrain 210 having a conventionalengine 12, a planetary transmission 214, and conventional final drivemechanism 16 is shown.

[0087] The planetary transmission 214 includes an input shaft 17continuously connected with the engine 12, a planetary gear arrangement218, and an output shaft 19 continuously connected with the final drivemechanism 16. The planetary gear arrangement 218 includes four planetarygear sets 220, 230, 240 and 250.

[0088] The planetary gear set 220 includes a sun gear member 222, a ringgear member 224, and a planet carrier assembly member 226. The planetcarrier assembly member 226 includes a plurality of pinion gears 227rotatably mounted on a carrier member 229 and disposed in meshingrelationship with both the sun gear member 222 and the ring gear member224.

[0089] The planetary gear set 230 includes a sun gear member 232, a ringgear member 234, and a planet carrier assembly member 236. The planetcarrier assembly member 236 includes a plurality of pinion gears 237rotatably mounted on a carrier member 239 and disposed in meshingrelationship with both the sun gear member 232 and the ring gear member234.

[0090] The planetary gear set 240 includes a sun gear member 242, a ringgear member 244, and a planet carrier assembly member 246. The planetcarrier assembly member 246 includes a plurality of intermeshing piniongears 247, 248 rotatably mounted on a carrier member 249 and disposed inmeshing relationship with the ring gear member 244 and the sun gearmember 242, respectively.

[0091] The planetary gear set 250 includes a sun gear member 252, a ringgear member 254, and a planet carrier assembly member 256. The planetcarrier assembly member 256 includes a plurality of intermeshing piniongears 257, 258 rotatably mounted on a carrier member 259 and disposed inmeshing relationship with the ring gear member 254 and the sun gearmember 252, respectively.

[0092] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 220, 230, 240 and 250 are divided into firstand second transmission subsets 260, 261 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 260 includes planetary gear sets 220 and 230, andtransmission subset 261 includes planetary gear sets 240 and 250. Theoutput shaft 19 is continuously connected with members of both subsets260 and 261.

[0093] As mentioned above, the first and second input clutches 262, 263are alternatively engaged for transmitting power from the input shaft 17to transmission subset 260 or transmission subset 261. The first andsecond input clutches 262, 263 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 260, 261 prior to engagingthe respective input clutches 262, 263. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms264, 265, 266, 267, 268, 269, 270, 271 and 272. The torque transmittingmechanism 264 comprises a braking synchronizer, and the torquetransmitting mechanisms 265, 266, 267, 268, 269, 270, 271 and 272comprise rotating synchronizers.

[0094] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 260, 261 (i.e. through clutch 262to synchronizers 265, 266, 267 and through clutch 263 to ring gearmember 244). The ring gear member 224 is continuously connected with thesun gear member 232 through the interconnecting member 274. The planetcarrier assembly member 246 is continuously connected with the ring gearmember 234 and the output shaft 19 through the interconnecting member276. The sun gear member 252 is continuously connected with thetransmission housing 280.

[0095] The planet carrier assembly member 226 is selectively connectablewith the transmission housing 280 through the braking synchronizer 264.The sun gear member 232 is selectively connectable with the input shaft17 through the input clutch 262 and the rotating synchronizer 265. Thesun gear member 222 is selectively connectable with the input shaft 17through the input clutch 262 and the rotating synchronizer 266. Theplanet carrier assembly member 236 is selectively connectable with theinput shaft 17 through the input clutch 262 and the rotatingsynchronizer 267. The planet carrier assembly member 226 is selectivelyconnectable with the planet carrier assembly member 236 through therotating synchronizer 268. The planet carrier assembly member 246 isselectively connectable with the ring gear member 254 through therotating synchronizer 269. The planet carrier assembly member 246 isselectively connectable with the planet carrier assembly member 256through the rotating synchronizer 270. The sun gear member 242 isselectively connectable with the ring gear member 254 through therotating synchronizer 271. The sun gear member 242 is selectivelyconnectable with the planet carrier assembly member 256 through therotating synchronizer 272.

[0096] As shown in FIG. 3b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio.

[0097] The reverse speed ratio is established with the engagement of theinput clutch 262, the braking synchronizer 264 and the rotatingsynchronizers 265, 268. The input clutch 262 and the rotatingsynchronizer 265 connect the sun gear member 232 to the input shaft 17.The braking synchronizer 264 connects the planet carrier assembly member226 to the transmission housing 280. The rotating synchronizer 268connects the planet carrier assembly member 226 to the planet carrierassembly member 236. The ring gear member 224 and the sun gear member232 rotate at the same speed as the input shaft 17. The planet carrierassembly members 226, 236 do not rotate. The ring gear member 234 andthe planet carrier assembly member 246 rotate at the same speed as theoutput shaft 19. The ring gear member 234, and therefore the outputshaft 19, rotates at a speed determined from the speed of the sun gearmember 232 and the ring gear/sun gear tooth ratio of the planetary gearset 230. The numerical value of the reverse speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set230.

[0098] The first forward speed ratio is established with the engagementof the input clutch 262, the braking synchronizer 264 and the rotatingsynchronizers 266, 268. The input clutch 262 and the rotatingsynchronizer 266 connect the sun gear member 222 to the input shaft 17.The braking synchronizer 264 connects the sun gear member 226 to thetransmission housing 280. The rotating synchronizer 268 connects theplanet carrier assembly member 226 to the planet carrier assembly member236. The sun gear member 222 rotates at the same speed as the inputshaft 17. The planet carrier assembly members 226, 236 do not rotate.The ring gear member 224 rotates at the same speed as the sun gearmember 232. The ring gear member 224 rotates at a speed determined fromthe speed of the sun gear member 222 and the ring gear/sun gear toothratio of the planetary gear set 220. The ring gear member 234 and theplanet carrier assembly member 246 rotate at the same speed as theoutput shaft 19. The ring gear member 234, and therefore the outputshaft 19, rotates at a speed determined from the speed of the sun gearmember 232 and the ring gear/sun gear tooth ratio of the planetary gearset 230. The numerical value of the first forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 220, 230.

[0099] The second forward speed ratio is established with the engagementof the input clutch 263 and the rotating synchronizers 269, 272. Theinput clutch 263 connects the ring gear member 244 to the input shaft17. The rotating synchronizer 269 connects the planet carrier assemblymember 246 to the ring gear member 254. The rotating synchronizer 272connects the sun gear member 242 to the planet carrier assembly member256. The sun gear member 242 rotates at the same speed as the planetcarrier assembly member 256. The planet carrier assembly member 246 andthe ring gear member 254 rotate at the same speed as the output shaft19. The ring gear member 244 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 246, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 244, the speed of the sun gear member 242 and the ringgear/sun gear tooth ratio of the planetary gear set 240. The sun gearmember 252 does not rotate. The planet carrier assembly member 256rotates at a speed determined from the speed of the ring gear member 254and the ring gear/sun gear tooth ratio of the planetary gear set 250.The numerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear set240, 250.

[0100] The third forward speed ratio is established with the engagementof the input clutch 262 and the rotating synchronizers 265, 267 and 268.In this configuration, the input shaft 17 is directly connected to theoutput shaft 19. The numerical value of the third forward speed ratio is1.

[0101] The fourth forward speed ratio is established with the engagementof the input clutch 263 and the rotating synchronizers 270, 271. Theinput clutch 263 connects the ring gear member 244 to the input shaft17. The rotating synchronizer 270 connects the planet carrier assemblymember 246 to the planet carrier assembly member 256. The rotatingsynchronizer 271 connects the sun gear member 242 to the ring gearmember 254. The sun gear member 242 rotates at the same speed as thering gear member 254. The planet carrier assembly members 246, 256rotate at the same speed as the output shaft 19. The ring gear member244 rotates at the same speed as the input shaft 17. The planet carrierassembly member 246, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 244, the speedof the sun gear member 242 and the ring gear/sun gear tooth ratio of theplanetary gear set 240. The sun gear member 252 does not rotate. Theplanet carrier assembly member 256 rotates at a speed determined fromthe speed of the ring gear member 254 and the ring gear/sun gear toothratio of the planetary gear set 250. The numerical value of the fourthforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 240, 250.

[0102] The fifth forward speed ratio is established with the engagementof the input clutch 262, the braking synchronizer 264 and the rotatingsynchronizers 266, 267. The input clutch 262 and the rotatingsynchronizers 266, 267 connect the sun gear member 222 and the planetcarrier assembly member 236 to the input shaft 17. The brakingsynchronizer 264 connects the planet carrier assembly member 226 to thetransmission housing 280. The sun gear member 222 and the planet carrierassembly member 236 rotate at the same speed as the input shaft 17. Theplanet carrier assembly member 226 does not rotate. The ring gear member224 rotates at the same speed as the sun gear member 232. The ring gearmember 224 rotates at a speed determined from the speed of the sun gearmember 222 and the ring gear/sun gear tooth ratio of the planetary gearset 220. The ring gear member 234 and the planet carrier assembly member246 rotate at the same speed as the output shaft 19. The ring gearmember 234, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 236, thespeed of the sun gear member 232 and the ring gear/sun gear tooth ratioof the planetary gear set 230. The numerical value of the fifth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 220, 230.

[0103] The sixth forward speed ratio is established with the engagementof the input clutch 263 and the rotating synchronizers 271, 272. Theinput clutch 263 connects the ring gear member 244 to the input shaft17. The rotating synchronizer 271 connects the sun gear member 242 tothe ring gear member 254. The rotating synchronizer 272 connects the sungear member 242 to the planet carrier assembly member 256. The sun gearmember 242 and the planetary gear set 250 do not rotate. The planetcarrier assembly member 246 rotates at the same speed as the outputshaft 19. The ring gear member 244 rotates at the same speed as theinput shaft 17. The planet carrier assembly member 246, and thereforethe output shaft 19, rotates at a speed determined from the speed of thering gear member 244 and the ring gear/sun gear tooth ratio of theplanetary gear set 240. The numerical value of the sixth forward speedratio is determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 240.

[0104] As previously set forth, the truth table of FIG. 3b describes thecombinations of engagements utilized for six forward speed ratios andone reverse speed ratio. The truth table also provides an example ofspeed ratios that are available with the family member described above.These examples of speed ratios are determined the tooth ratios given inFIG. 3b. The R1/S1 value is the tooth ratio of the planetary gear set220; the R2/S2 value is the tooth ratio of the planetary gear set 230;the R3/S3 value is the tooth ratio of the planetary gear set 240; andthe R4/S4 value is the tooth ratio of the planetary gear set 250. Alsodepicted in FIG. 3b is a chart representing the ratio steps betweenadjacent forward speed ratios and the reverse speed ratio. For example,the first to second ratio interchange has a step of 1.82.

[0105] A powertrain 310, shown in FIG. 4a, includes the engine 12, aplanetary transmission 314, and the final drive mechanism 16. Theplanetary transmission 314 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 318, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 318 includes four planetary gear sets320, 330, 340 and 350.

[0106] The planetary gear set 320 includes a sun gear member 322, a ringgear member 324, and a planet carrier assembly member 326. The planetcarrier assembly member 326 includes a plurality of pinion gears 327rotatably mounted on a carrier member 329 and disposed in meshingrelationship with both the sun gear member 322 and the ring gear member324.

[0107] The planetary gear set 330 includes a sun gear member 332, a ringgear member 334, and a planet carrier assembly member 336. The planetcarrier assembly member 336 includes a plurality of pinion gears 337rotatably mounted on a carrier member 339 and disposed in meshingrelationship with both the sun gear member 332 and the ring gear member334.

[0108] The planetary gear set 340 includes a sun gear member 342, a ringgear member 344, and a planet carrier assembly member 346. The planetcarrier assembly member 346 includes a plurality of intermeshing piniongears 347, 348 rotatably mounted on a carrier member 349 and disposed inmeshing relationship with the ring gear member 344 and the sun gearmember 342, respectively.

[0109] The planetary gear set 350 includes a sun gear member 352, a ringgear member 354, and a planet carrier assembly member 356. The planetcarrier assembly member 356 includes a plurality of intermeshing piniongears 357, 358 rotatably mounted on a carrier member 359 and disposed inmeshing relationship with the ring gear member 354 and the sun gearmember 352, respectively.

[0110] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 320, 330, 340 and 350 are divided into firstand second transmission subsets 360, 361 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 360 includes planetary gear sets 320 and 330, andtransmission subset 361 includes planetary gear sets 340 and 350. Theoutput shaft 19 is continuously connected with members of both subsets360 and 361.

[0111] As mentioned above, the first and second input clutches 362, 363are alternatively engaged for transmitting power from the input shaft 17to transmission subset 360 or transmission subset 361. The first andsecond input clutches 362, 363 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 360, 361 prior to engagingthe respective input clutches 362, 363. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms364, 365, 366, 367, 368, 369, 370, 371 and 372. The torque transmittingmechanism 364 comprises a braking synchronizer, and the torquetransmitting mechanisms 365, 366, 367, 368, 369, 370, 371 and 372comprise rotating synchronizers.

[0112] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 360, 361 (i.e. through clutch 362to synchronizers 365, 366, 367 and through clutch 363 to ring gearmember 344). The ring gear member 324 is continuously connected with thesun gear member 332 through the interconnecting member 374. The planetcarrier assembly member 346 is continuously connected with the ring gearmember 334 and the output shaft 19 through the interconnecting member376. The planet carrier assembly member 356 is continuously connectedwith the transmission housing 380.

[0113] The planet carrier assembly member 326 is selectively connectablewith the transmission housing 380 through the braking synchronizer 364.The sun gear member 332 is selectively connectable with the input shaft17 through the input clutch 362 and the rotating synchronizer 365. Thesun gear member 322 is selectively connectable with the input shaft 17through the input clutch 362 and the rotating synchronizer 366. Theplanet carrier assembly member 336 is selectively connectable with theinput shaft 17 through the input clutch 362 and the rotatingsynchronizer 367. The planet carrier assembly member 326 is selectivelyconnectable with the planet carrier assembly member 336 through therotating synchronizer 368. The planet carrier assembly member 346 isselectively connectable with the ring gear member 354 through therotating synchronizer 369. The planet carrier assembly member 346 isselectively connectable with the sun gear member 352 through therotating synchronizer 370. The sun gear member 342 is selectivelyconnectable with the ring gear member 354 through the rotatingsynchronizer 371. The sun gear member 342 is selectively connectablewith the sun gear member 352 through the rotating synchronizer 372.

[0114] The truth tables given in FIGS. 4b, 5 b, 6 b, 7 b, 8 b and 9 bshow the engagement sequences for the torque transmitting mechanisms toprovide at least five forward speed ratios and one reverse speed ratio.As shown and described above for the configurations in FIGS. 1a, 2 a and3 a, those skilled in the art will understand from the respective truthtables how the speed ratios are established through the planetary gearsets identified in the written description.

[0115] The truth table shown in FIG. 4b describes the engagementcombination and engagement sequence necessary to provide the reversedrive ratio and six forward speed ratios. A sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 4b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 4b. The R1/S1 value is the tooth ratio for theplanetary gear set 320; the R2/S2 value is the tooth ratio for theplanetary gear set 330; the R3/S3 value is the tooth ratio for theplanetary gear set 340; and the R4/S4 value is the tooth ratio for theplanetary gear set 350. Also given in FIG. 4b is a chart describing thestep ratios between the adjacent forward speed ratios and the reverse tofirst forward speed ratio. For example, the first to second forwardspeed ratio step is 2.02.

[0116] Those skilled in the art will recognize that the numerical valueof the reverse speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 330. The numerical values ofthe first and fifth forward speed ratios are determined utilizing thering gear/sun gear tooth ratios of the planetary gear sets 320, 330. Thenumerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 340, 350. The numerical value of the third forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 340.

[0117] A powertrain 410 shown in FIG. 5a includes a conventional engine12, a planetary transmission 414, and a conventional final drivemechanism 16. The planetary transmission 414 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 418, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 418 includes four planetary gear sets420, 430, 440 and 450.

[0118] The planetary gear set 420 includes a sun gear member 422, a ringgear member 424, and a planet carrier assembly member 426. The planetcarrier assembly member 426 includes a plurality of intermeshing piniongears 427, 428 rotatably mounted on a carrier member 429 and disposed inmeshing relationship with the ring gear member 424 and the sun gearmember 422, respectively.

[0119] The planetary gear set 430 includes a sun gear member 432, a ringgear member 434, and a planet carrier assembly member 436. The planetcarrier assembly member 436 includes a plurality of pinion gears 437rotatably mounted on a carrier member 439 and disposed in meshingrelationship with both the sun gear member 432 and the ring gear member434.

[0120] The planetary gear set 440 includes a sun gear member 442, a ringgear member 444, and a planet carrier assembly member 446. The planetcarrier assembly member 446 includes a plurality of intermeshing piniongears 447, 448 rotatably mounted on a carrier member 449 and disposed inmeshing relationship with the ring gear member 444 and the sun gearmember 442, respectively.

[0121] The planetary gear set 450 includes a sun gear member 452, a ringgear member 454, and a planet carrier assembly member 456. The planetcarrier assembly member 456 includes a plurality of intermeshing piniongears 457, 458 rotatably mounted on a carrier member 459 and disposed inmeshing relationship with the ring gear member 454 and the sun gearmember 452, respectively.

[0122] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 420, 430, 440 and 450 are divided into firstand second transmission subsets 460, 461 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 460 includes planetary gear sets 420 and 430, andtransmission subset 461 includes planetary gear sets 440 and 450. Theoutput shaft 19 is continuously connected with members of both subsets460 and 461.

[0123] As mentioned above, the first and second input clutches 462, 463are alternatively engaged for transmitting power from the input shaft 17to transmission subset 460 or transmission subset 461. The first andsecond input clutches 462, 463 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 460, 461 prior to engagingthe respective input clutches 462, 463. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms464, 465, 466, 467, 468, 469, 470, 471 and 472. The torque transmittingmechanisms 464 comprises a braking synchronizer, and the torquetransmitting mechanisms 465, 466, 467, 468, 469, 470, 471 and 472comprise rotating synchronizers.

[0124] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 460, 461 (i.e. through clutch 462to synchronizers 465, 466, 467 and through clutch 463 to ring gearmember 444). The planet carrier assembly member 426 is continuouslyconnected with the sun gear member 432 through the interconnectingmember 474. The planet carrier assembly member 446 is continuouslyconnected with the ring gear member 434 and the output shaft 19 throughthe interconnecting member 476. The sun gear member 452 is continuouslyconnected with the transmission housing 480.

[0125] The ring gear member 424 is selectively connectable with thetransmission housing 480 through the braking synchronizer 464. Theplanet carrier assembly member 426 is selectively connectable with theinput shaft 17 through the input clutch 462 and the rotatingsynchronizer 465. The sun gear member 422 is selectively connectablewith the input shaft 17 through the input clutch 462 and the rotatingsynchronizer 466. The planet carrier assembly member 436 is selectivelyconnectable with the input shaft 17 through the input clutch 462 and therotating synchronizer 467. The ring gear member 424 is selectivelyconnectable with the planet carrier assembly member 436 through therotating synchronizer 468. The planet carrier assembly member 446 isselectively connectable with the ring gear member 454 through therotating synchronizer 469. The planet carrier assembly member 446 isselectively connectable with the planet carrier assembly member 456through the rotating synchronizer 470. The sun gear member 442 isselectively connectable with the ring gear member 454 through therotating synchronizer 471. The sun gear member 442 is selectivelyconnectable with the planet carrier assembly member 456 through therotating synchronizer 472.

[0126] As shown in FIG. 5b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio.

[0127]FIG. 5b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first ratio. For example, theratio step between the first and second forward ratios is 1.75. Thoseskilled in the art will recognize that the numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear set 430. The numerical values of the firstand fifth forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 420, 430. Thenumerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 440, 450. The numerical value of the third forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 440.

[0128] A powertrain 510, shown in FIG. 6a, includes a conventionalengine 12, a powertrain 514, and a conventional final drive mechanism16. The powertrain 514 includes an input shaft 17 connected with theengine 12, a planetary gear arrangement 518, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 518 includes four planetary gear sets 520, 530, 540 and550.

[0129] The planetary gear set 520 includes a sun gear member 522, a ringgear member 524, and a planet carrier assembly member 526. The planetcarrier assembly member 526 includes a plurality of intermeshing piniongears 527, 528 rotatably mounted on a carrier member 529 and disposed inmeshing relationship with the ring gear member 524 and the sun gearmember 522, respectively.

[0130] The planetary gear set 530 includes a sun gear member 532, a ringgear member 534, and a planet carrier assembly member 536. The planetcarrier assembly member 536 includes a plurality of pinion gears 537rotatably mounted on a carrier member 539 and disposed in meshingrelationship with both the sun gear member 532 and the ring gear member534.

[0131] The planetary gear set 540 includes a sun gear member 542, a ringgear member 544, and a planet carrier assembly member 546. The planetcarrier assembly member 546 includes a plurality of intermeshing piniongears 547, 548 rotatably mounted on a carrier member 549 and disposed inmeshing relationship with the ring gear member 544 and the sun gearmember 542, respectively.

[0132] The planetary gear set 550 includes a sun gear member 552, a ringgear member 554, and a planet carrier assembly member 556. The planetcarrier assembly member 556 includes a plurality of intermeshing piniongears 557, 558 rotatably mounted on a carrier member 559 and disposed inmeshing relationship with the ring gear member 554 and the sun gearmember 552, respectively.

[0133] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 520, 530, 540 and 550 are divided into firstand second transmission subsets 560, 561 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 560 includes planetary gear sets 520 and 530, andtransmission subset 561 includes planetary gear sets 540 and 550. Theoutput shaft 19 is continuously connected with members of both subsets560 and 561.

[0134] As mentioned above, the first and second input clutches 562, 563are alternatively engaged for transmitting power from the input shaft 17to transmission subset 560 or transmission subset 561. The first andsecond input clutches 562, 563 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 560, 561 prior to engagingthe respective input clutches 562, 563. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms564, 565, 566, 567, 568, 569, 570, 571 and 572. The torque transmittingmechanisms 564 comprises a braking synchronizer, and the torquetransmitting mechanisms 565, 566, 567, 568, 569, 570, 571 and 572comprise rotating synchronizers.

[0135] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 560, 561 (i.e. through clutch 562to synchronizers 565, 566, 567 and through clutch 563 to ring gearmember 544). The planet carrier assembly member 526 is continuouslyconnected with the sun gear member 532 through the interconnectingmember 574. The planet carrier assembly member 546 is continuouslyconnected with the ring gear member 534 and the output shaft 19 throughthe interconnecting member 576. The planet carrier assembly member 556is continuously connected with the transmission housing 580.

[0136] The ring gear member 524 is selectively connectable with thetransmission housing 580 through the braking synchronizer 564. Theplanet carrier assembly member 526 is selectively connectable with theinput shaft 17 through the input clutch 562 and the rotatingsynchronizer 565. The sun gear member 522 is selectively connectablewith the input shaft 17 through the input clutch 562 and the rotatingsynchronizer 566. The planet carrier assembly member 536 is selectivelyconnectable with the input shaft 17 through the input clutch 562 and therotating synchronizer 567. The sun gear member 524 is selectivelyconnectable with the planet carrier assembly member 536 through therotating synchronizer 568. The planet carrier assembly member 546 isselectively connectable with the ring gear member 554 through therotating synchronizer 569. The planet carrier assembly member 546 isselectively connectable with the sun gear member 552 through therotating synchronizer 570. The sun gear member 542 is selectivelyconnectable with the ring gear member 554 through the rotatingsynchronizer 571. The sun gear member 542 is selectively connectablewith the sun gear member 552 through the rotating synchronizer 572.

[0137] As shown in FIG. 6b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio. The chart of FIG. 6bdescribes the ratio steps between adjacent forward speed ratios and theratio step between the reverse and first forward speed ratio.

[0138] Those skilled in the art, upon reviewing the truth table and theschematic representation of FIG. 6a can determine that the numericalvalue of the reverse speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 530. The numericalvalues of the first and fifth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets520, 530. The numerical values of the second and fourth forward speedratios are determined utilizing the ring gear/sun gear tooth ratios ofthe planetary gear sets 540, 550. The numerical value of the thirdforward speed ratio is 1. The numerical value of the sixth forward speedratio is determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 540.

[0139] The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6b. R1/S1 value isthe tooth ratio of the planetary gear set 520; the R2/S2 value is thetooth ratio of the planetary gear set 530; the R3/S3 value is the toothratio of the planetary gear set 540; and the R4/S4 value is the toothratio of the planetary gear set 550.

[0140] A powertrain 610, shown in FIG. 7a, has the engine 12, aplanetary transmission 614, and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618, and the output shaft 19. The planetary gear arrangement618 includes four planetary gear sets 620, 630, 640 and 650.

[0141] The planetary gear set 620 includes a sun gear member 622, a ringgear member 624, and a planet carrier assembly member 626. The planetcarrier assembly member 626 includes a plurality of pinion gears 627rotatably mounted on a carrier member 629 and disposed in meshingrelationship with both the sun gear member 622 and the ring gear member624.

[0142] The planetary gear set 630 includes a sun gear member 632, a ringgear member 634, and a planet carrier assembly member 636. The planetcarrier assembly member 636 includes a plurality of pinion gears 637rotatably mounted on a carrier member 639 and disposed in meshingrelationship with both the sun gear member 632 and the ring gear member634.

[0143] The planetary gear set 640 includes a sun gear member 642, a ringgear member 644, and a planet carrier assembly member 646. The planetcarrier assembly member 646 includes a plurality of intermeshing piniongears 647, 648 rotatably mounted on a carrier member 649 and disposed inmeshing relationship with the ring gear member 644 and the sun gearmember 642, respectively.

[0144] The planetary gear set 650 includes a sun gear member 652, a ringgear member 654, and a planet carrier assembly member 656. The planetcarrier assembly member 656 includes a plurality of pinion gears 657rotatably mounted on a carrier member 659 and disposed in meshingrelationship with both the sun gear member 652 and the ring gear member654.

[0145] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 620, 630, 640 and 650 are divided into firstand second transmission subsets 660, 661 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 660 includes planetary gear sets 620 and 630, andtransmission subset 661 includes planetary gear sets 640 and 650. Theoutput shaft 19 is continuously connected with members of both subsets660 and 661.

[0146] As mentioned above, the first and second input clutches 662, 663are alternatively engaged for transmitting power from the input shaft 17to transmission subset 660 or transmission subset 661. The first andsecond input clutches 662, 663 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 660, 661 prior to engagingthe respective input clutches 662, 663. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes nine torque transmitting mechanisms664, 665, 666, 667, 668, 669, 670, 671 and 672. The torque transmittingmechanism 664 comprises a braking synchronizer, and the torquetransmitting mechanisms 665, 666, 667, 668, 669, 670, 671 and 672comprise rotating synchronizers.

[0147] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 660, 661 (i.e. through clutch 662to synchronizers 665, 666, and through clutch 663 to ring gear member644). The planet carrier assembly member 626 is continuously connectedwith the ring gear member 634 through the interconnecting member 674.The planet carrier assembly member 646 is continuously connected withthe ring gear member 624 and the output shaft 19 through theinterconnecting member 676. The planet carrier assembly member 656 iscontinuously connected with the transmission housing 680.

[0148] The sun gear member 622 is selectively connectable with thetransmission housing 680 through the braking synchronizer 664. The sungear member 632 is selectively connectable with the input shaft 17through the input clutch 662 and the rotating synchronizer 665. Theplanet carrier assembly member 636 is selectively connectable with theinput shaft 17 through the input clutch 662 and the rotatingsynchronizer 666. The sun gear member 622 is selectively connectablewith the sun gear member 632 through the rotating synchronizer 667. Thering gear member 624 is selectively connectable with the planet carrierassembly member 636 through the rotating synchronizer 668. The planetcarrier assembly member 646 is selectively connectable with the ringgear member 654 through the rotating synchronizer 669. The planetcarrier assembly member 646 is selectively connectable with the sun gearmember 652 through the rotating synchronizer 670. The sun gear member642 is selectively connectable with the ring gear member 654 through therotating synchronizer 671. The sun gear member 642 is selectivelyconnectable with the sun gear member 652 through the rotatingsynchronizer 672.

[0149] As shown in FIG. 7b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide sixforward speed ratios and a reverse speed ratio. The ratio values givenare by way example and are established utilizing the ring gear/sun geartooth ratios given in FIG. 7b. For example, the R1/S2 value is the toothratio of the planetary gear set 620; the R2/S2 value is the tooth ratioof the planetary gear set 630; the R3/S3 value is the tooth ratio of theplanetary gear set 640; and the R4/S4 value is the tooth ratio of theplanetary gear set 650. The ratio steps between adjacent forward ratiosand the reverse to first ratio are also given in FIG. 7b.

[0150] Those skilled in the art will, upon reviewing the truth table ofFIG. 7b, recognize that the numerical values of the reverse and thesixth forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 640, 650. The numericalvalues of the first and fifth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets620, 630. The numerical value of the second forward speed ratio is 1.The numerical value of the third forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set620. The numerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set640.

[0151] A powertrain 710, shown in FIG. 8a, has the conventional engine12, a planetary transmission 714, and the conventional final drivemechanism 16. The engine 12 is continuously connected with the inputshaft 17. The planetary transmission 714 is drivingly connected with thefinal drive mechanism 16 through the output shaft 19. The planetarytransmission 714 includes a planetary gear arrangement 718 that has afirst planetary gear set 720, a second planetary gear set 730, a thirdplanetary gear set 740, and a fourth planetary gear set 750.

[0152] The planetary gear set 720 includes a sun gear member 722, a ringgear member 724, and a planet carrier assembly member 726. The planetcarrier assembly member 726 includes a plurality of pinion gears 727rotatably mounted on a carrier member 729 and disposed in meshingrelationship with both the sun gear member 722 and the ring gear member724.

[0153] The planetary gear set 730 includes a sun gear member 732, a ringgear member 734, and a planet carrier assembly member 736. The planetcarrier assembly member 736 includes a plurality of pinion gears 737rotatably mounted on a carrier member 739 and disposed in meshingrelationship with both the sun gear member 732 and the ring gear member734.

[0154] The planetary gear set 740 includes a sun gear member 742, a ringgear member 744, and a planet carrier assembly member 746. The planetcarrier assembly member 746 includes a plurality of intermeshing piniongears 747, 748 rotatably mounted on a carrier member 749 and disposed inmeshing relationship with the ring gear member 744 and the sun gearmember 742, respectively.

[0155] The planetary gear set 750 includes a sun gear member 752, a ringgear member 754, and a planet carrier assembly member 756. The planetcarrier assembly member 756 includes a plurality of pinion gears 757rotatably mounted on a carrier member 759 and disposed in meshingrelationship with both the sun gear member 752 and the ring gear member754.

[0156] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 720, 730, 740 and 750 are divided into firstand second transmission subsets 760, 761 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 760 includes planetary gear sets 720 and 730, andtransmission subset 761 includes planetary gear, sets 740 and 750. Theoutput shaft 19 is continuously connected with a member of transmissionsubset 761.

[0157] In this family member, which is a derivative of the family membershown in FIG. 1a, rather than having two input clutches and ninesynchronizers, four input clutches and seven synchronizers are utilizedto achieve reduced content. The first input clutch and first, second andthird synchronizers in FIG. 1a are here operatively replaced by a first,second and third input clutch 765, 766, 767 and the second input clutchin FIG. 1a remains here as a third input clutch 763. The input clutches763, 765, 766 and 767 are controlled electronically, and the disengagedinput clutch is gradually engaged while the engaged input clutch isgradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 760, 761 prior to engagingthe respective input clutch 763, 765, 766 or 767. The preselection isachieved by means of electronically controlled synchronizers. As shown,the planetary gear arrangement includes six torque transmittingmechanisms 764, 768, 769, 770, 771 and 772. The torque transmittingmechanisms 764 comprises a braking synchronizer, and the torquetransmitting mechanisms 768, 769, 770, 771 and 772 comprise rotatingsynchronizers.

[0158] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 760, 761 (i.e. through clutch 765to sun gear member 732, through clutch 766 to sun gear member 722,through clutch 767 to planet carrier assembly member 736, and throughclutch 763 to ring gear member 744). The ring gear member 724 iscontinuously connected with the sun gear member 732 through theinterconnecting member 774. The planet carrier assembly member 746 iscontinuously connected with the ring gear member 734 and the outputshaft 19 through the interconnecting member 776. The ring gear member754 is continuously connected with the transmission housing 780.

[0159] The planet carrier assembly member 726 is selectively connectablewith the transmission housing 780 through the braking synchronizer 764.The sun gear member 732 is selectively connectable with the input shaft17 through the clutch 765. The sun gear member 722 is selectivelyconnectable with the input shaft 17 through the clutch 766. The planetcarrier assembly member 736 is selectively connectable with the inputshaft 17 through the input clutch 767. The planet carrier assemblymember 726 is selectively connectable with the planet carrier assemblymember 736 through the rotating synchronizer 768. The planet carrierassembly member 746 is selectively connectable with the planet carrierassembly member 756 through the rotating synchronizer 769. The planetcarrier assembly member 746 is selectively connectable with the sun gearmember 752 through the rotating synchronizer 770. The sun gear member742 is selectively connectable with the planet carrier assembly member756 through the rotating synchronizer 771. The sun gear member 742 isselectively connectable with the sun gear member 752 through therotating synchronizer 772.

[0160] As shown in FIG. 8b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. Also given in the truth table isa set of numerical values that are attainable with the present inventionutilizing the ring gear/sun gear tooth ratios given in FIG. 8b. TheR1/S1 value is the tooth ratio of the planetary gear set 720; the R2/S2value is the tooth ratio of the planetary gear set 730; the R3/S3 valueis the tooth ratio of the planetary gear set 740; and the R4/S4 value isthe tooth ratio of the planetary gear set 750.

[0161]FIG. 8b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.95.

[0162] Those skilled in the art will recognize that the numerical valueof the reverse speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 730. The numerical values ofthe first and fifth forward speed ratios are determined utilizing thering gear/sun gear tooth ratios of the planetary gear sets 720, 730. Thenumerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 740, 750. The numerical value of the third forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 740.

[0163]FIGS. 9a and 9 b illustrate a transmission wherein one of thetorque transmitting mechanisms from a previously described configurationis eliminated to realize five forward speed ratios and a reverse speedratio. Specifically, the powertrain 810, shown in FIG. 9a is identicalto that shown in FIG. 7a, except that the rotating synchronizer 670 ofFIG. 7a has been eliminated.

[0164] A powertrain 810, shown in FIG. 9a, has the conventional engine12, a planetary transmission 814, and the final drive mechanism 16. Theengine 12 is continuously connected with the input shaft 17. Theplanetary transmission 814 is drivingly connected with final drivemechanism 16 through output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, a third planetary gearset 840, and fourth planetary gear set 850.

[0165] The planetary gear set 820 includes a sun gear member 822, a ringgear member 824, and a planet carrier assembly member 826. The planetcarrier assembly member 826 includes a plurality of pinion gears 827rotatably mounted on a carrier member 829 and disposed in meshingrelationship with both the sun gear member 822 and the ring gear member824.

[0166] The planetary gear set 830 includes a sun gear member 832, a ringgear member 834, and a planet carrier assembly member 836. The planetcarrier assembly member 836 includes a plurality of pinion gears 837rotatably mounted on a carrier member 839 and disposed in meshingrelationship with both the sun gear member 832 and the ring gear member834.

[0167] The planetary gear set 840 includes a sun gear member 842, a ringgear member 844, and a planet carrier assembly member 846. The planetcarrier assembly member 846 includes a plurality of intermeshing piniongears 847, 848 rotatably mounted on a carrier member 849 and disposed inmeshing relationship with the ring gear member 844 and the sun gearmember 842, respectively.

[0168] The planetary gear set 850 includes a sun gear member 852, a ringgear member 854, and a planet carrier assembly member 856. The planetcarrier assembly member 856 includes a plurality of pinion gears 857rotatably mounted on a carrier member 859 and disposed in meshingrelationship with both the sun gear member 852 and the ring gear member854.

[0169] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 820, 830, 840 and 850 are divided into firstand second transmission subsets 860, 861 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 860 includes planetary gear sets 820 and 830, andtransmission subset 861 includes planetary gear sets 840 and 850. Theoutput shaft 19 is continuously connected with members of both subsets860 and 861.

[0170] As mentioned above, the first and second input clutches 862, 863are alternatively engaged for transmitting power from the input shaft 17to transmission subset 860 or transmission subset 861. The first andsecond input clutches 862, 863 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratioselection is preselected within the transmission subsets 860, 861 priorto engaging the respective input clutches 862, 863. The preselection isachieved by means of electronically controlled synchronizers. As shown,the planetary gear arrangement includes eight torque transmittingmechanisms 864, 865, 866, 867, 868, 869, 871 and 872. The torquetransmitting mechanism 864 comprises a braking synchronizer, and thetorque transmitting mechanisms 865, 866, 867, 868, 869, 871 and 872comprise rotating synchronizers.

[0171] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 860, 861 (i.e. through clutch 862to synchronizers 865, 866, and through clutch 863 to ring gear member844). The planet carrier assembly member 826 is continuously connectedwith the ring gear member 834 through the interconnecting member 874.The planet carrier assembly member 846 is continuously connected withthe ring gear member 824 and the output shaft 19 through theinterconnecting member 876. The planet carrier assembly member 856 iscontinuously connected with the transmission housing 880.

[0172] The sun gear member 822 is selectively connectable with thetransmission housing 880 through the braking synchronizer 864. The sungear member 832 is selectively connectable with the input shaft 17through the input clutch 862 and the rotating synchronizer 865. Theplanet carrier assembly member 836 is selectively connectable with theinput shaft 17 through the input clutch 862 and the rotatingsynchronizer 866. The sun gear member 822 is selectively connectablewith the sun gear member 832 through the rotating synchronizer 867. Thering gear member 824 is selectively connectable with the planet carrierassembly member 836 through the rotating synchronizer 868. The planetcarrier assembly member 846 is selectively connectable with the ringgear member 854 through the rotating synchronizer 869. The sun gearmember 842 is selectively connectable with the ring gear member 854through the rotating synchronizer 871. The sun gear member 842 isselectively connectable with the sun gear member 852 through therotating synchronizer 872.

[0173] As shown in FIG. 9b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of at least three to provide fiveforward speed ratios and a reverse speed ratio. A sample of numericalvalues for the individual ratios is also given in the truth table ofFIG. 9b. These numerical values have been calculated using the ringgear/sun gear tooth ratios also given by way of example in FIG. 9b. TheR1/S1 value is the tooth ratio of the planetary gear set 820; the R2/S2value is the tooth ratio of planetary gear set 830; the R3/S3 value isthe tooth ratio of the planetary gear set 840; and the R4/S4 value isthe tooth ratio of the planetary gear set 850. FIG. 9b also describesthe ratio steps between adjacent forward ratios and between the reverseand first forward ratio. For example, the ratio step between the firstand second forward ratios is 1.60. Those skilled in the art willrecognize that the numerical value of the reverse speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 840, 850. The numerical values of the first andfifth forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 820, 830. The numericalvalue of the second forward speed ratio is 1. The numerical value of thethird forward speed ratio is determined utilizing the ring gear/sun geartooth ratio of the planetary gear set 820. The numerical value of thefourth forward speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 840.

[0174] While the best modes for carrying out the invention have beendescribed in detail, those familiar with the art to which this inventionrelates will recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second, third and fourth planetary gear sets each havingfirst, second and third members; a first interconnecting membercontinuously interconnecting said first member of said first planetarygear set with said first member of said second planetary gear set; asecond interconnecting member continuously interconnecting a member ofsaid first or second planetary gear set with said first member of saidthird planetary gear set and said output shaft; said first member ofsaid fourth planetary gear set being continuously connected with astationary member; a first input clutch continuously connected with saidinput shaft; a second input clutch selectively interconnecting saidinput shaft with said second member of said third planetary gear set;first and second torque-transmitting mechanisms selectivelyinterconnecting members of said first and second planetary gear setswith said first input clutch; third and fourth torque-transmittingmechanisms selectively interconnecting members of said first and secondplanetary gear sets with other members of said first or second planetarygear set or with said first input clutch; fifth, sixth, seventh andeighth torque-transmitting mechanisms selectively interconnectingmembers of said third planetary gear set with said second and thirdmembers of said fourth planetary gear set; a ninth torque-transmittingmechanism selectively interconnecting a member of said first or secondplanetary gear set, that is not continuously connected with said outputshaft, with said stationary member; and said input clutches andtorque-transmitting mechanisms being engaged in combinations of at leastthree to provide at least six forward speed ratios and a reverse speedratio.
 2. The transmission defined in claim 1, wherein said ninetorque-transmitting mechanisms comprise synchronizers.
 3. Thetransmission defined in claim 1, wherein said ninth torque-transmittingmechanism comprises a braking synchronizer, and said first, second,third, fourth, fifth, sixth, seventh and eighth torque-transmittingmechanisms comprise rotating synchronizers.
 4. The transmission definedin claim 1, wherein said first input clutch is applied for odd numberspeed ranges and said second input clutch is applied for even numberspeed ranges.
 5. The transmission defined in claim 1, wherein said firstinput clutch is applied for even number speed ranges and said secondinput clutch is applied for odd number speed ranges.
 6. The transmissiondefined in claim 1, wherein said first input clutch and said secondinput clutch are interchangeable to shift from odd number speed rangesto even number speed ranges, and vice versa.
 7. The transmission definedin claim 1, wherein selected ones of said nine torque-transmittingmechanisms are engaged prior to gear shifting to achieve shiftingwithout torque interruptions.
 8. The transmission defined in claim 1,wherein at least two of said synchronizers comprise a doublesynchronizer to reduce cost and package size.
 9. A multi-speedtransmission comprising: an input shaft; an output shaft; first, second,third and fourth planetary gear sets each having first, second and thirdmembers; a first interconnecting member continuously interconnectingsaid first member of said first planetary gear set with said firstmember of said second planetary gear set; a second interconnectingmember continuously interconnecting a member of said first or secondplanetary gear set with said first member of said third planetary gearset and said output shaft; said first member of said fourth planetarygear set being continuously connected with a stationary member; a firstinput clutch continuously connected with said input shaft; a secondinput clutch selectively interconnecting said input shaft with saidsecond member of said third planetary gear set; nine torque-transmittingmechanisms for selectively interconnecting said members of said first,second, third or fourth planetary gear sets with said first inputclutch, said output shaft, said first or second interconnecting member,said stationary member or with other members of said planetary gearsets, said input clutches and nine torque-transmitting mechanisms beingengaged in combinations of at least three to establish at least sixforward speed ratios and a reverse speed ratio between said input shaftand said output shaft.
 10. The transmission defined in claim 9, whereinfirst and second of said nine torque-transmitting mechanisms areselectively operable for interconnecting members of said first or secondplanetary gear sets with said first input clutch.
 11. The transmissiondefined in claim 9, wherein third and fourth of said ninetorque-transmitting mechanisms are selectively operable forinterconnecting members of said first or second planetary gear sets withother members of said first or second planetary gear set, or with saidfirst input clutch.
 12. The transmission defined in claim 9, whereinfifth, sixth, seventh and eighth of said nine torque-transmittingmechanisms are selectively operable for interconnecting members of saidthird planetary gear set with said second and third members of saidfourth planetary gear set.
 13. The transmission defined in claim 9,wherein a ninth of said nine torque-transmitting mechanisms is operablefor selectively interconnecting a member of said first or secondplanetary gear set, that is not continuously connected with said outputshaft, with said stationary member.
 14. The transmission defined inclaim 9, wherein planet carrier assembly members of a plurality of saidplanetary gear sets are of the single pinion type.
 15. The transmissiondefined in claim 9, wherein planet carrier assembly members of aplurality of said planetary gear sets are of the double pinion type. 16.The transmission defined in claim 9, wherein each of said ninetorque-transmitting mechanisms comprises a synchronizer.
 17. Thetransmission defined in claim 9, wherein said first input clutch isapplied for odd number speed ranges and said second input clutch isapplied for even number speed ranges.
 18. The transmission defined inclaim 9, wherein said first input clutch is applied for even numberspeed ranges and said second input clutch is applied for odd numberspeed ranges.
 19. The transmission defined in claim 9, wherein selectedones of said nine torque-transmitting mechanisms are engaged prior togear shifting to achieve shifting without torque interruptions.
 20. Amulti-speed transmission comprising: an input shaft; an output shaft;first, second, third and fourth planetary gear sets each having first,second and third members; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set; a secondinterconnecting member continuously interconnecting a member of saidfirst or second planetary gear set with said first member of said thirdplanetary gear set and said output shaft; said first member of saidfourth planetary gear set being continuously connected with a stationarymember; first and second torque-transmitting mechanisms selectivelyinterconnecting members of said first and second planetary gear set withsaid input shaft and, therefore, alternately functioning as a firstinput clutch; a second input clutch selectively interconnecting saidinput shaft with said second member of said third planetary gear set;third and fourth torque-transmitting mechanisms selectivelyinterconnecting members of said first or second planetary gear sets withother members of said first or second planetary gear set, or with saidinput shaft; fifth, sixth, seventh and eighth torque-transmittingmechanisms selectively interconnecting members of said third planetarygear set with said second and third members of said fourth planetarygear set; a ninth torque-transmitting mechanism selectivelyinterconnecting a member of said first or second planetary gear sets,that is not continuously connected with said output shaft, with saidstationary member; and said input clutches and torque-transmittingmechanisms being engaged in combinations of at least three to provide atleast six forward speed ratios and a reverse speed ratio.
 21. Thetransmission defined in claim 20, wherein said nine torque-transmittingmechanisms comprise synchronizers.
 22. The transmission defined in claim20, wherein said first input clutch is applied for odd number speedranges and said second input clutch is applied for even number speedranges.
 23. The transmission defined in claim 20, wherein said firstinput clutch is applied for even number speed ranges and said secondinput clutch is applied for odd number speed ranges.
 24. Thetransmission defined in claim 20, wherein said first input clutch andsaid second input clutch are interchangeable to shift from odd numberspeed ranges to even number speed ranges, and vice versa.
 25. Thetransmission defined in claim 20, wherein selected ones of said ninetorque-transmitting mechanisms are engaged prior to gear shifting toachieve shifting without torque interruptions.
 26. The transmissiondefined in claim 20, wherein at least two of said synchronizers comprisea double synchronizer to reduce cost and package size.
 27. A multi-speedtransmission comprising: an input shaft; an output shaft; first, second,third and fourth planetary gear sets each having first, second and thirdmembers; a first interconnecting member continuously interconnectingsaid first member of said first planetary gear set with said firstmember of said second planetary gear set; a second interconnectingmember continuously interconnecting a member of said first or secondplanetary gear set with said first member of said third planetary gearset and said output shaft; said first member of said fourth planetarygear set being continuously connected with a stationary member; a firstinput clutch continuously connected with said input shaft; a secondinput clutch selectively interconnecting said input shaft with saidsecond member of said third planetary gear set; eighttorque-transmitting mechanisms for selectively interconnecting saidmembers of said first, second, third or fourth planetary gear sets withsaid first input clutch, said output shaft, said first or secondinterconnecting member, said stationary member or with other members ofsaid planetary gear sets, said input clutches and eighttorque-transmitting mechanisms being engaged in combinations of at leastthree to establish at least five forward speed ratios and a reversespeed ratio between said input shaft and said output shaft.
 28. Thetransmission defined in claim 27, wherein first and second of said eighttorque-transmitting mechanisms are selectively operable forinterconnecting members of said first or second planetary gear sets withsaid first input clutch.
 29. The transmission defined in claim 27,wherein third and fourth of said eight torque-transmitting mechanismsare selectively operable for interconnecting members of said first orsecond planetary gear sets with other members of said first or secondplanetary gear set, or with said first input clutch.
 30. Thetransmission defined in claim 27, wherein fifth, sixth and seventh andof said eight torque-transmitting mechanisms are selectively operablefor interconnecting members of said third planetary gear set withmembers of said fourth planetary gear set.
 31. The transmission definedin claim 27, wherein an eighth of said eight torque-transmittingmechanisms is operable for selectively interconnecting a member of saidfirst or second planetary gear set, that is not continuously connectedwith said output shaft, with said stationary member.
 32. Thetransmission defined in claim 27, wherein planet carrier assemblymembers of a plurality of said planetary gear sets are of the singlepinion type.
 33. The transmission defined in claim 27, wherein planetcarrier assembly members of a plurality of said planetary gear sets areof the double pinion type.
 34. The transmission defined in claim 27,wherein each of said eight torque-transmitting mechanisms comprises asynchronizer.
 35. The transmission defined in claim 27, wherein saidfirst input clutch is applied for odd number speed ranges and saidsecond input clutch is applied for even number speed ranges.
 36. Thetransmission defined in claim 27, wherein said first input clutch isapplied for even number speed ranges and said second input clutch isapplied for odd number speed ranges.
 37. The transmission defined inclaim 27, wherein selected ones of said eight torque-transmittingmechanisms are engaged prior to gear shifting to achieve shiftingwithout torque interruptions.